must use specific class but can't use tikz

Hey,

I just love tikz and want to use it to make the pics for my thesis.
Trouble is I am supposed to use \documentclass{uicthesi}, a style that carries instructions how my thesis will be formatted. Then when I load \usepackage{tikz} and use

\begin{figure}

\end{figure}
I get an error, it says too many }

There is no problem when I use \documentclass{article}. Everything compiles.
Can you help?
Petar Manolov